public CrawlArgs(CrawlContext crawlContext)
{
if (crawlContext == null)
throw new ArgumentNullException("crawlContext");
CrawlContext = crawlContext;
}
public PageCrawlCompletedArgs(CrawlContext crawlContext, CrawledPage crawledPage)
: base(crawlContext)
{
if (crawledPage == null)
throw new ArgumentNullException("crawledPage");
CrawledPage = crawledPage;
}
public PageLinksCrawlDisallowedArgs(CrawlContext crawlContext, CrawledPage crawledPage, string disallowedReason)
: base(crawlContext, crawledPage)
{
if (string.IsNullOrWhiteSpace(disallowedReason))
throw new ArgumentNullException("disallowedReason");
DisallowedReason = disallowedReason;
}
public PageCrawlStartingArgs(CrawlContext crawlContext, PageToCrawl pageToCrawl)
: base(crawlContext)
{
if (pageToCrawl == null)
throw new ArgumentNullException("pageToCrawl");
PageToCrawl = pageToCrawl;
}
public PageCrawlDisallowedArgs(CrawlContext crawlContext, PageToCrawl pageToCrawl, string disallowedReason)
: base(crawlContext, pageToCrawl)
{
if (string.IsNullOrWhiteSpace(disallowedReason))
throw new ArgumentNullException("disallowedReason");
DisallowedReason = disallowedReason;
}
public virtual CrawlDecision ShouldCrawlPageLinks(CrawledPage crawledPage, CrawlContext crawlContext)
{
if (crawledPage == null)
return new CrawlDecision { Allow = false, Reason = "Null crawled page" };
if (crawlContext == null)
return new CrawlDecision { Allow = false, Reason = "Null crawl context" };
if (string.IsNullOrWhiteSpace(crawledPage.RawContent))
return new CrawlDecision { Allow = false, Reason = "Page has no content" };
if (!crawlContext.CrawlConfiguration.IsExternalPageLinksCrawlingEnabled && !crawledPage.IsInternal)
return new CrawlDecision { Allow = false, Reason = "Link is external" };
if (crawledPage.CrawlDepth >= crawlContext.CrawlConfiguration.MaxCrawlDepth)
return new CrawlDecision { Allow = false, Reason = "Crawl depth is above max" };
return new CrawlDecision { Allow = true };
}
public virtual CrawlDecision ShouldCrawlPage(PageToCrawl pageToCrawl, CrawlContext crawlContext)
{
if (pageToCrawl == null)
return new CrawlDecision { Allow = false, Reason = "Null page to crawl" };
if (crawlContext == null)
return new CrawlDecision { Allow = false, Reason = "Null crawl context" };
if (pageToCrawl.CrawlDepth > crawlContext.CrawlConfiguration.MaxCrawlDepth)
return new CrawlDecision { Allow = false, Reason = "Crawl depth is above max" };
if (!pageToCrawl.Uri.Scheme.StartsWith("http"))
return new CrawlDecision { Allow = false, Reason = "Scheme does not begin with http" };
if (!crawlContext.CrawlConfiguration.IsUriRecrawlingEnabled &&
crawlContext.CrawledUrls.ContainsKey(pageToCrawl.Uri.AbsoluteUri))
return new CrawlDecision { Allow = false, Reason = "Link already crawled" };
if (crawlContext.CrawledUrls.Count + 1 > crawlContext.CrawlConfiguration.MaxPagesToCrawl)
{
crawlContext.IsCrawlStopRequested = true;
return new CrawlDecision { Allow = false, Reason = string.Format("MaxPagesToCrawl limit of [{0}] has been reached", crawlContext.CrawlConfiguration.MaxPagesToCrawl) };
}
int pagesCrawledInThisDomain = 0;
if (crawlContext.CrawlConfiguration.MaxPagesToCrawlPerDomain > 0 &&
crawlContext.CrawlCountByDomain.TryGetValue(pageToCrawl.Uri.Authority, out pagesCrawledInThisDomain) &&
pagesCrawledInThisDomain > 0)
{
if (pagesCrawledInThisDomain >= crawlContext.CrawlConfiguration.MaxPagesToCrawlPerDomain)
return new CrawlDecision { Allow = false, Reason = string.Format("MaxPagesToCrawlPerDomain limit of [{0}] has been reached for domain [{1}]", crawlContext.CrawlConfiguration.MaxPagesToCrawlPerDomain, pageToCrawl.Uri.Authority) };
}
if (!crawlContext.CrawlConfiguration.IsExternalPageCrawlingEnabled && !pageToCrawl.IsInternal)
return new CrawlDecision { Allow = false, Reason = "Link is external" };
return new CrawlDecision { Allow = true };
}
/// <summary>
/// Creates a crawler instance with custom settings or implementation. Passing in null for all params is the equivalent of the empty constructor.
/// </summary>
/// <param name="threadManager">Distributes http requests over multiple threads</param>
/// <param name="scheduler">Decides what link should be crawled next</param>
/// <param name="httpRequester">Makes the raw http requests</param>
/// <param name="hyperLinkParser">Parses a crawled page for it's hyperlinks</param>
/// <param name="crawlDecisionMaker">Decides whether or not to crawl a page or that page's links</param>
/// <param name="crawlConfiguration">Configurable crawl values</param>
public WebCrawler(
CrawlConfiguration crawlConfiguration,
ICrawlDecisionMaker crawlDecisionMaker,
IThreadManager threadManager,
IScheduler scheduler,
IPageRequester httpRequester,
IHyperLinkParser hyperLinkParser,
IMemoryManager memoryManager)
{
_crawlContext = new CrawlContext();
_crawlContext.CrawlConfiguration = crawlConfiguration ?? GetCrawlConfigurationFromConfigFile() ?? new CrawlConfiguration();
CrawlBag = _crawlContext.CrawlBag;
_threadManager = threadManager ?? new ManualThreadManager(_crawlContext.CrawlConfiguration.MaxConcurrentThreads);
_scheduler = scheduler ?? new FifoScheduler(_crawlContext.CrawlConfiguration.IsUriRecrawlingEnabled);
_httpRequester = httpRequester ?? new PageRequester(_crawlContext.CrawlConfiguration);
_crawlDecisionMaker = crawlDecisionMaker ?? new CrawlDecisionMaker();
if (_crawlContext.CrawlConfiguration.MaxMemoryUsageInMb > 0
|| _crawlContext.CrawlConfiguration.MinAvailableMemoryRequiredInMb > 0)
_memoryManager = memoryManager ?? new MemoryManager(new CachedMemoryMonitor(new GcMemoryMonitor(), _crawlContext.CrawlConfiguration.MaxMemoryUsageCacheTimeInSeconds));
_hyperLinkParser = hyperLinkParser ?? new HapHyperLinkParser();
_crawlContext.Scheduler = _scheduler;
}
public virtual CrawlDecision ShouldDownloadPageContent(CrawledPage crawledPage, CrawlContext crawlContext)
{
if (crawledPage == null)
return new CrawlDecision { Allow = false, Reason = "Null crawled page" };
if (crawlContext == null)
return new CrawlDecision { Allow = false, Reason = "Null crawl context" };
if (crawledPage.HttpWebResponse == null)
return new CrawlDecision { Allow = false, Reason = "Null HttpWebResponse" };
if (crawledPage.HttpWebResponse.StatusCode != HttpStatusCode.OK)
return new CrawlDecision { Allow = false, Reason = "HttpStatusCode is not 200" };
string pageContentType = crawledPage.HttpWebResponse.ContentType.ToLower().Trim();
bool isDownloadable = false;
foreach (string downloadableContentType in crawlContext.CrawlConfiguration.DownloadableContentTypes.Split(','))
{
if (pageContentType.Contains(downloadableContentType.ToLower().Trim()))
{
isDownloadable = true;
break;
}
}
if (!isDownloadable)
return new CrawlDecision { Allow = false, Reason = "Content type is not any of the following: " + crawlContext.CrawlConfiguration.DownloadableContentTypes };
if (crawlContext.CrawlConfiguration.MaxPageSizeInBytes > 0 && crawledPage.HttpWebResponse.ContentLength > crawlContext.CrawlConfiguration.MaxPageSizeInBytes)
return new CrawlDecision { Allow = false, Reason = string.Format("Page size of [{0}] bytes is above the max allowable of [{1}] bytes", crawledPage.PageSizeInBytes, crawlContext.CrawlConfiguration.MaxPageSizeInBytes) };
return new CrawlDecision { Allow = true };
}
